1. Field of the Invention
The present invention relates to a light positioning frame, and more particularly to light positioning frame for a back light module so as to obviate uneven light effect on a liquid crystal display which is held by the light positioning frame.
2. Description of the Prior Art
In order to clearly show pictures from a liquid crystal display, a light source is provided by a back light module. The back light module is composed of a light source positioning frame and a mask having the light source securely positioned therein. A light guiding plate having a reflective film on the rear side of the light guiding plate is provided to the light source positioning frame and has the light source securely mounted at ends of the light guiding plate such that light from the light source is able to emit from sides of the light guiding plate. Through the reflective film, pictures on the liquid crystal display is clearly shown due to the light from the light source.
The conventional structure of the light source positioning frame is shown in FIG. 6, and has a mask (60) and a positioning frame (70). The mask (60) is securely connected to a bottom face of the positioning frame (70) via bolts. The mask (60) is composed of a light source cap (61) and a bottom plate (63) integrally formed at a bottom of the light source cap (61). When the mask (60) is assembled with the positioning frame (70), the light source cap (61) is securely connected to a bottom face of a top frame (71) of the positioning frame (70) via an adhesive tape (62). Then the bottom plate (63) and the light source cap (61) are used to clamp a light guiding plate (81) therebetween.
Due to the requirements to clearly present pictures from the liquid crystal display, the material for making the mask is a kind of metal having a light reflecting characteristic. As such, when the light source cap (61) and the bottom plate (63) are used to clamp the light guiding plate (81), light from a light source (80), preferably a light emitting diode (LED), travels from peripheral sides of the light guiding plate (81) and thus creates a linear spot light effect to the liquid crystal display module (90). That is, a line of light appears on the display. The linear spot light effect causes uneven light reflection on the liquid crystal display which is quite annoying and disturbance. In order to obviate the shortcoming, an opaque layer is provided to the bottom of the light source cap (61) to dim the light at the peripheral sides of the light guiding plate (81) such that the dispersed light on the liquid crystal display is even. However, the addition of the opaque layer increases the manufacture cost and the application of the adhesive tape (62) to secure the mask (60) to the positioning frame (70) is disadvantageous to the disassembly.
To overcome the shortcomings, the present invention tends to provide an improved light positioning frame to mitigate the aforementioned problems.